The present invention relates generally to filter systems and, more particularly, to a submersible filter system for handling fluids having radioactive contaminants in an underwater environment.
In a nuclear reactor power facility having a pool containing water to serve as a shield against radiation from a source within the pool it is sometimes necessary to conduct operations within the pool which are productive of particulate matter and gases having entrained contaminants. For example, such contaminants may be generated by underwater operation of an electrical discharge machine (EDM). The waste product of the underwater EDM process comprises a stream of pool water with entrained contaminated particulate matter and vented gases which effluent stream must be filtered to eliminate the contaminants before the water of the effluent stream is permitted to re-enter the pool.
Typically, the filtration is performed by a series or bank of relatively small filter cartridges rather than a single and relatively large filter element for the reason that there are dimensional limitations imposed by the structure provided for disposing of the contaminated filter cartridges. More specifically, an underwater tunnel of small cross sectional area leads from the main pool to an underwater adjacent facility in which spent cartridges are deposited within a containment vessel or cask of small cross sectional area which, when filled with a plurality of the spent filter cartridges, is moved to a burial site. When a spent filter cartridge is removed from a filter apparatus within the pool it is sometimes necessary that it be rotated 90.degree. before it can pass through the connecting tunnel and after it has exited the tunnel it is manipulated to an erect position to permit insertion into the waste containment vessel. Since the contaminated dangerously radioactive filter cartridge must be manipulated remotely it is possible that contaminated residue may escape from within the cartridge as it is lifted out of the filter apparatus, tilted to a horizontal position to align its long axis with the tunnel, and then re-adjusted to vertical position. In addition, the filter cartridge itself may be dropped or come into contact with some rigid structure which may break the cartridge or due to impact may dislodge contaminated material from within the cartridge and release it into the pool.